Frac-ball with exothermic reaction constituents

ABSTRACT

A frac-ball, a system including the frac-ball, and a method using the frac-ball are provided. The frac-ball includes a body and an exothermic reaction initiator. The frac-ball body includes a material having at least two dissimilar metallic constituents, which dissimilar metallic constituents are configured to permit an exothermic reaction there between. The exothermic reaction initiator is in communication with the body, and is configured to selectively initiate an exothermic reaction between the two dissimilar metallic constituents.

This application claims priority to U.S. Patent Appln. No. 62/609,694 filed Dec. 22, 2017, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION 1. Technical Field

The present disclosure relates to subterranean well casing segmentation devices in general, and to frac-balls for use in well casing segmentation devices, well casing segmentation device systems using frac-balls, and methods related thereto in particular.

2. Background Information

Subterranean wells can be used to locate and extract subterranean disposed raw materials. For example, wells may be used to locate and extract hydrocarbon materials (e.g., hydrocarbon fluids such as oil, and gases such as natural gas) from subterranean deposits. A water well may be used for locating and extracting potable or non-potable water from an underground water table. A well configured and located to locate and extract hydrocarbon materials typically includes a tubular casing disposed subsurface within the well, and pumping system for injecting materials into and for extracting materials out of the well. The casing may be oriented to have vertically disposed sections, horizontally disposed sections, and sections having a combined vertical and horizontal orientation.

The term “hydraulic fracturing” refers to well formation techniques (sometimes referred to as “well completion” techniques) that create fractures within the subterranean ground to facilitate extraction of hydrocarbon materials disposed within the subterranean ground. There are several hydraulic fracturing techniques currently used, including techniques that utilize fluid flow segmentation devices.

For example, “plug and perforation” techniques may utilize one or more plugs (a type of casing segmentation device) that are positionable within the well casing. The plugs are used to fluidically isolate casing sections (i.e., segment the casing into “zones”) for a variety of reasons; e.g., to permit specific casing sections to be radially perforated, etc. The perforations in the casing provide fluid paths for materials to selectively exit and enter a fluid passage within the casing. In some instances, the plugs are designed to include a fluid flow passage that permits fluid flow through the plug; i.e., between a forward end of the plug and an aft end of the plug. The passage has a ball seat disposed at or near the forward end of the passage. The term “forward end” refers to the end of the plug fluid flow passage disposed closest to the well head when disposed within the casing, and the term “aft end” refers to the end of the plug fluid flow passage disposed farthest from the well head when disposed within the casing. The passage ball seat is configured to receive a ball (sometimes referred to as a “frac-ball”). To segment the well casing, a frac-ball is introduced into the casing and the frac-ball is carried with fluid flow until it reaches the ball seat. Once the frac-ball is seated properly within the seat, the frac-ball closes the plug fluid passage and prevents fluid passage through the plug. The fluid on one side of the plug may then be increased dramatically in pressure; e.g., to perform the perforation/fracturing process.

Once all of the zones are fractured, it is necessary to remove the frac-balls to permit fluid travel within the casing. It is known in the prior art to machine out a frac-ball and ball seat, but such a process is time-consuming and expensive. It is also known in the prior art to use a frac-ball made of a material that dissolves or erodes over time within the well fluid environment. These methods are not desirable because the dissolving or eroding process takes a considerable amount of time. In fact, the rate of dissolution or erosion can vary significantly depending on environmental conditions within the well, and consequently it may be unclear whether a frac-ball is removed or not at a given point in time. These type frac-balls also do not remove the ball seat. As a result, the balls seat can act as a flow impediment.

What is needed is a frac-ball, a well casing segmentation system, and method that overcome the issues associated with existing technology.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present disclosure, a frac-ball is provided that includes a body and an exothermic reaction initiator. The frac-ball body comprises a material having at least two dissimilar metallic constituents, which dissimilar metallic constituents are configured to permit an exothermic reaction there between. The exothermic reaction initiator is in communication with the body, and is configured to selectively initiate an exothermic reaction between the two dissimilar metallic constituents.

According to another aspect of the present disclosure, a well casing segmentation system is provided. The system includes a segmentation device and at least one frac-ball. The frac-ball is according to the aspect described above. The frac-ball is configured to function as a seal within the segmentation device disposed in a well casing environment prior to an exothermic reaction, and subsequent to an exothermic reaction is incapable of functioning as a seal within the segmentation device disposed in the well casing environment.

According to another aspect of the present disclosure, a method of operating a segmentation device disposed within a well casing is provided. The method includes providing a segmentation device and a frac-ball according to the aspects described above. The method further includes disposing a frac-ball in communication with the segmentation device to create a fluidic seal within the segmentation device, wherein said fluidic seal substantially prevents fluid flow through the segmentation device, and selectively actuating the exothermic reaction initiator to initiate an exothermic reaction between the at least two dissimilar metallic constituents.

According to any of the above aspects and embodiments thereof, the at least two dissimilar metallic constituents may be configured to participate in an alloying reaction there between upon being subjected to an input from the exothermic reaction initiator.

According to any of the above aspects and embodiments, the at least two dissimilar metallic constituents may be present within the material in relative amounts sufficient to sustain the exothermic reaction.

According to any of the above aspects and embodiments, the at least two dissimilar metallic constituents may include an aluminum metallic constituent and a magnesium metallic constituent.

According to any of the above aspects and embodiments, the body may have a shell configuration with an interior cavity.

According to any of the above aspects and embodiments, the body may have a solid body configuration.

According to any of the above aspects and embodiments, the exothermic reaction initiator may include a trigger mechanism.

According to any of the above aspects and embodiments, the exothermic reaction initiator may include a trigger mechanism that includes one or more of a pressure sensor, a temperature sensor, and a timing device.

According to any of the above aspects and embodiments, the trigger mechanism may be used to sense pressure within a well casing environment and to actuate the trigger mechanism upon sensing a well casing environment pressure at or above a predetermined pressure.

According to any of the above aspects and embodiments, the trigger mechanism may be used to sense temperature within a well casing environment and to actuate the trigger mechanism upon sensing a well casing environment temperature at or above a predetermined temperature.

According to any of the above aspects and embodiments, the trigger mechanism may be used to determine an amount of time passing subsequent to an occurrence of a predetermined event, and to actuate the trigger mechanism upon a determination of a predetermined amount of time passing subsequent to the predetermined event.

The present method and advantages associated therewith will become more readily apparent in view of the detailed description provided below, including the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional diagrammatic illustration of a portion of a well casing.

FIG. 2 is a diagrammatic illustration of a casing segmentation device.

FIG. 3 is a diagrammatic illustration of a sliding sleeve type casing segmentation device shown in a closed configuration.

FIG. 4 is a diagrammatic illustration of a sliding sleeve type casing segmentation device shown in an open configuration.

FIG. 5 is a diagrammatic cross-section of a frac-ball embodiment.

FIG. 6 is a diagrammatic cross-section of a frac-ball embodiment.

FIG. 7 is a phase diagram of an aluminum-magnesium (Al—Mg) composition.

FIG. 8 is a chart showing thermal analysis data acquired using differential scanning calorimetry/thermogravimetric techniques, with the ordinate on the left side of the graph indicating thermogravimetric weight change percentage and the ordinate on the right side of the graph indicating thermal flow in terms of energy/mass.

DETAILED DESCRIPTION

Now referring to FIG. 1, an exemplary embodiment of a wellbore 20 disposed in a subterranean formation is shown. The wellbore 20 includes a fluid conduit (typically referred to as a “casing”; e.g., casing 22) disposed within a drilled bore extending below surface level 24. The wellbore 20 is diagrammatically shown as having a substantially vertical oriented section 26, a substantially horizontal oriented section 28, and an arcuate section 30 connecting the vertical and horizontal sections 26, 28. The present disclosure is not limited to use with any well bore configuration relative to the surface. For purposes of describing aspects of the present disclosure, the casing 22 is described herein as including casing segmentation devices 32, packers 34, and pipe sections 36. The pipe sections 36 include a wall 38 that surrounds and defines an internal flow passage 40. The described well casing configuration reflects a typical configuration and the present disclosure is not limited to any particular well casing configuration. The casing 22 is disposed within the well after the well is drilled. The wellbore 20 is shown as having cement 42 disposed between the outer diameter of the casing 22 and the inner diameter of the drilled bore, which cement 42 secures the casing 22 within the drilled bore. Not all wellbores include cement or other material disposed outside of the casing 22.

As indicated above, a well completion process that utilizes hydraulic fracturing involves creating fractures 44 (e.g., cavities, fluid passages, etc.) within the subterranean ground adjacent the casing 22 to facilitate extraction of hydrocarbon materials (or water) disposed within the subterranean ground. The fracturing process is typically performed in segments (sometimes referred to as “stages” or “zones”); e.g., a first segment of the casing 22 may be created adjacent the portion of the wellbore 20 furthest from the wellhead 46, and the casing 22 in that segment “perforated” to create one or more fluid paths between the casing flow passage 40 and the subterranean environment adjacent the segment. Once the first segment is fractured, that segment may be isolated, and the process may be repeated for the next segment in line, until the all of the desired segments of the wellbore 20 are fractured. The term “perforated”, as used herein, refers to the creation of the aforesaid fluid paths between the casing flow passage 40 and the subterranean environment adjacent the segment. In some instances, a pipe section 36 of the casing 22 is perforated by creating holes in the wall 38 of the pipe section 36 (e.g., using a perforating gun or a sliding sleeve type device). The present disclosure is not limited to use with any particular device or method for creating the fractures within the subterranean environment.

Aspects of the present disclosure include frac-balls 48 as described herein, casing segmentation systems that include a casing segmentation device 32 configured to be used with a frac-ball 48 as described herein, and methods associated therewith. The present disclosure is not limited to use with any particular type of segmentation device 32 that uses a frac-ball 48 to provide a sealed configuration. Referring to FIGS. 2-4, diagrammatic illustrations of exemplary casing segmentation devices 32 are shown positionally located within a well casing 22. These devices may include an internal passage 76 with a forward end 78, and aft end 80, and a ball seat 82 disposed at the forward end 78. Once a frac-ball 48 is seated properly within the ball seat 82, the frac-ball 48 closes the fluid passage 76 and prevents fluid passing there through. As stated above, the present disclosure is not limited to use with any particular type of segmentation device 32 that uses a frac-ball 48 to provide a sealed configuration. Non-limiting examples of segmentations devices that include a ball seat include those disclosed in U.S. Pat. Nos. 7,628,210; 7,637,323; and 7,673,677, and U.S. Patent Publication No. 2009/0044948, each of which is hereby incorporated by reference in its entirety.

According to aspects of the present disclosure, a frac-ball 48 comprises a material that is mechanically compromised upon the occurrence of an exothermic reaction. The destructible frac-ball 48 (hereinafter referred to as “frac-ball 48” for convenience) may be described as having a pre-event form and a post-event form. The term “pre-event form” as used herein refers to the form of the frac-ball 48 after manufacture but prior to any exothermic reaction as will be described below. In the pre-event form, the frac-ball 48 possesses one or more mechanical properties adequate to permit the frac-ball 48 to function as a segmentation device sealing element in a well environment. The term “post-event form” as used herein refers to the form of the frac-ball 48 after an exothermic reaction has occurred as will be described below. In the post-event form, the frac-ball material has sufficiently changed so that the frac-ball 48 is no longer adequate to function as a segmentation device sealing element in a well environment post event; e.g., the material comprising the frac-ball 48 has changed, and one or more of the mechanical properties of the frac-ball material has changed.

The frac-ball 48 includes a body 50 and at least one exothermic reaction initiator 52. The frac-ball body 50 is not limited to any particular geometric configuration. For example, in some embodiments (e.g., see FIG. 5) the body 50 may be a shell configuration having one or more walls 54, with each wall having an exterior surface 56 and an interior surface 58. The interior surface(s) 58 of the wall(s) 54 defines an enclosed interior cavity 60. As another example, the frac-ball body 50 may be configured as a solid body; e.g., see FIG. 6. The frac-ball 48 may have any exterior configuration that permits it to function as a segmentation device sealing element in a well environment. A non-limiting typical exterior configuration is a spherical body.

In pre-event form, the frac-ball body 50 may comprise a material having a plurality of dissimilar metallic constituents (e.g., a first metallic constituent, a second metallic constituent, etc.) that can be processed into a material form and geometric configuration that permits the frac-ball body 50 to function as a segmentation device sealing element in a well environment. In some embodiments, the frac-ball body material may include one or more non-metal constituents as well. At least two of the plurality of metallic constituents present within the material are capable of participating in an exothermic reaction between one another (e.g., an alloying or intermetallic reaction there between). The at least two metallic constituents are present within the material in relative stoichiometric amounts that are sufficient to permit an exothermic reaction there between, and are preferably distributed within the frac-ball body 50 in a manner that will permit the exothermic reaction to self-propagate throughout the frac-ball body 50. As will be explained below, the exothermic reaction may be initiated by thermal energy produced by an exothermic reaction initiator 52. The pre-event frac-ball material is stable under typical well environment conditions.

The term “metallic constituent” as used herein may mean a single metallic element (e.g., Al, Ni, Mg, etc.), or a material that consists essentially of a single metallic element, or may be an alloy formed of a plurality of dissimilar metallic elements. The present disclosure is not limited to any material having a plurality of metallic constituents, or to any particular metallic constituents.

A non-limiting example of an acceptable pre-event frac-ball material includes an aluminum (Al) metallic constituent and a magnesium (Mg) metallic constituent. As stated above, the aluminum constituent and the magnesium constituent are present within the pre-event frac-ball material in relative amounts capable of participating in an exothermic reaction there between, and are preferably distributed within the frac-ball body 50 in a manner that will permit the exothermic reaction to propagate throughout the frac-ball body 50. For example, a pre-event frac-ball material may include discrete bodies of magnesium disposed within a laminar aluminum matrix. In some embodiments, the distribution of the discrete magnesium bodies within the aluminum matrix may be relatively uniform, but a relatively uniform distribution is not required. A relative uniform distribution of magnesium within an aluminum matrix may facilitate propagation of an exothermic reaction between the two constituents throughout the frac-ball material. The present disclosure is not limited to this Al—Mg example of a pre-event frac-ball material. Additional non-limiting examples of a pre-event frac-ball material include other metallic combinations such as titanium and boron, zirconium and nickel, etc. An array of intermetallic combinations that may be used within a pre-event frac-ball material and their theoretical heat outputs associated with alloying are described by Fischer and Grubelich (Theoretical Energ Release of Thermites, Intermetallics, and Combustible Metals presented at the 24^(th) International Pyrotechnics Seminar, Monterey, Calif. 1998)

As stated above, the above described pre-event Al—Mg frac-ball material is capable of participating in an alloying reaction. The phase diagram shown in FIG. 7 is a phase diagram that illustrates aluminum (Al) as an independent element on the left side of the diagram, and magnesium (Mg) as an independent element on the right side of the diagram. The center lower portion of the diagram illustrates different solid phase Al—Mg alloys that may be formed in an alloying reaction. In this Al—Mg example,

Shavings of an Al—Mg material were subjected to a simultaneous thermal analysis, using differential scanning calorimetry/thermogravimetric techniques. The analysis was conducted in an argon environment. The results of the analysis are depicted in FIG. 8. Line 66 illustrates thermal flow for a first analysis run, and line 68 illustrates thermal flow for a second analysis run (i.e., indicated by the ordinate on the right side of the graph of FIG. 8), as determined by differential scanning calorimetry (“DSC”). Line 70 illustrates thermogravimetric analysis weight percentage thermal flow for the first analysis, and line 72 illustrates thermogravimetric analysis weight percentage thermal flow for the second analysis (i.e., indicated by the ordinate on the left side of the graph of FIG. 8). The data lines 66-72 indicate a highly exothermic reaction occurring at about five hundred and ninety degrees Celsius (590° C.) with negligible mass gain. These results are indicative of an intermetallic reaction between the Al metallic constituent and the Mg metallic constituent and are consistent with the Al—Mg phase diagram shown in FIG. 7.

The present disclosure is not limited to any particular methodology for forming the pre-event material into a frac-ball 48. Acceptable methodologies for forming a pre-event frac-ball 48 may vary depending upon the particular constituency of the material (e.g., the specific types of metallic constituents, etc.) and/or the geometric characteristics of the frac-ball 48. An isostatic pressing process is a non-limiting example of a methodology that may be used to form a pre-event frac-ball 48. Isostatic pressing is a powder metallurgy forming process that applies equal pressure in all directions on a powder compact, typically to achieve uniformity of density and microstructure. Isostatic pressing methodologies include cold isostatic pressing (“CIP”) and hot isostatic pressing (“HIP”), either of which may be used to form a pre-event frac-ball 48. When an isostatic pressing methodology is used, the frac-ball material (including the metallic constituents therein) may be initially in a powder form. Upon completion of the isostatic pressing process, the powder materials are pressed into a solid form that can be used as a frac-ball 48; i.e., into a form that is capable of functioning as a segmentation device sealing element in a well environment. In this form, the frac-ball material is stable under typical well environment conditions; e.g., typical well conditions alone will not initiate an exothermic reaction between metallic constituents within the frac-ball material. The present disclosure is not limited to using an isostatic pressing process to form a pre-event frac-ball 48.

As stated above, embodiments of the present frac-ball 48 include at least one exothermic reaction initiator 52 that is configured to provide sufficient thermal energy to initiate an exothermic alloying or intermetallic reaction between at least two metallic constituents within the pre-event frac-ball material. The present disclosure is not limited to any particular type of exothermic reaction initiator 52; e.g., the initiator 52 may be an electrical, mechanical, or chemical device, or some combination thereof. A non-limiting example of an exothermic reaction initiator 52 is one that includes a pyrotechnic composition commonly referred to as “thermite”; e.g., a pyrotechnic composition that includes aluminum with iron oxide or silicon with lead oxide. An exothermic reaction initiator 52 may be disposed within a pre-event frac-ball 48 (e.g., in an interior cavity), or it may be disposed completely or partially within a pre-event frac-ball wall 54, or some combination thereof, etc. The present disclosure is not limited to any particular positioning of an exothermic reaction initiator 52.

In some embodiments, the exothermic reaction initiator 52 may include a trigger mechanism 74 that is configured to cause the exothermic reaction initiator 52 to actuate, which exothermic reaction initiator 52 in turn causes the exothermic reaction within the pre-event frac-ball material. A trigger mechanism 74 may assume a variety of different forms, and the present disclosure is not limited to any particular type of trigger mechanism 74. An acceptable trigger mechanism 74 may include an environmental sensor (e.g., a pressure or temperature sensor), a timing device, appropriate circuitry, a power source (e.g., a battery), etc., including combinations thereof. In those trigger mechanism 74 embodiments that include circuitry, the circuitry may include one or more processing devices (e.g., a microprocessor, a micro-controller, a digital signal processor, a central processing unit, a field programmable gate array, a programmable logic device, logic circuitry, analog circuitry, digital circuitry, etc.) and a memory device storing instructions executable by the processing device. As a non-limiting example, a trigger mechanism 74 may be configured to transfer energy from a power source (e.g., electrical current) to a device configured to actuate the exothermic reaction initiator 52 upon the occurrence of an event; e.g., expiration of a predetermined period of time, or a sensed pressure, or a sensed temperature, etc., or any combination thereof. Initiation of the exothermic reaction initiator 52, in turn, is adequate to initiate the alloying or intermetallic reaction that causes pre-event frac-ball material to change to a post-event form.

In regards to a trigger mechanism 74 that utilizes a temperature sensor, some wells have well portions where the subterranean environment is at elevated temperature. In these applications, the fracturing fluid that is being pumped from the surface may be no warmer than a known temperature (e.g., 80° F.) and during fracturing the aforesaid fluid will maintain a frac-ball 48 at a temperature that is cooler than the surrounding well environment; e.g., the fracking fluid acts as a coolant. Once the fracturing operation at a stage is complete, the warmer temperature reservoir fluids and gases will raise the temperature of the frac-ball 48 via thermal conduction and/or convection. In this instance, the trigger mechanism 74 may be an aspect that is disabled below a predetermined temperature, and enabled at temperatures above the predetermined temperature. Once the temperature sensor detects a predetermined temperature (e.g., “a trigger temperature”), the electronic component may directly or indirectly cause the exothermic reaction initiator 52 to actuate.

Another type of trigger mechanism 74 is one that is activated by pressure; e.g., when a pressure sensor portion of the trigger mechanism 74 senses a predetermined environmental pressure, the trigger mechanism 74 is activated. The predetermined pressure could, for example, be the high pressure resultant from a fracturing operation or it could simply be the hydrostatic pressure exerted by the column of fluid in the well.

Another type of trigger mechanism 74 is one that activates upon receipt or termination of a selectively emitted signal. For example, the trigger mechanism 74 may be selectively activated by radio frequency energy type signal, or an acoustic energy type signal (e.g., ultrasonic signal), a pressure pulse type signal traveling through the fracturing fluid, etc.

Another type of trigger mechanism 74 is one that actuates based on timing; e.g., the trigger mechanism 74 can be programmed to initiate at a particular time, or after a predetermined interval of time (e.g., a time delay period starting from when the frac-ball 48 is deployed into the well).

Another type of trigger mechanism 74 is one that may be selectively activated via electromagnetic inductive coupling; e.g., selectively activated by the application or removal of a magnetic field.

A trigger mechanism 74 may in some embodiments, use a combination of two or more of the above trigger mechanism 74 configurations described above; e.g., once a predetermined temperature or pressure is sensed, a timer element may be activated that causes the trigger mechanism 74 to actuate after a predetermined period of time, etc. The present disclosure is not limited to any of the trigger mechanisms described above. U.S. Patent Publication No. 2016/0130906, which is commonly assigned and is hereby incorporated by reference in its entirety, describes examples of trigger mechanisms 74 that may be used with the present disclosure.

As stated above, a frac-ball 48 in pre-event form according to the present disclosure is capable of functioning as a segmentation device sealing element in a well environment, and is stable under typical well environment conditions. The term “stable” as used here means that absent the introduction of an amount of thermal energy (or other type of energy) into the pre-event frac-ball material adequate to initiate an exothermic reaction between two or more metallic constituents within the frac-ball material, no exothermic reaction will occur.

During use of a frac-ball 48 according to the various embodiments described herein, the frac-ball 48 is introduced into the well casing and is positioned relative to a segmentation device (e.g., received within a “seat”) in a manner that substantially prevents fluid flow through the segmentation device. Upon the occurrence of one or more predetermined events (e.g., the perforation/fracturing process is completed in a given well casing segment, etc.), the circumstances (e.g., predetermined pressure, temperature, signal, time, etc.) that are required to initiate the exothermic reaction initiator 52 are produced. Subsequently, the exothermic reaction initiator 52 actuates and thereby initiates an exothermic reaction between two or more metallic constituents within the pre-event frac-ball material. As described above, the exothermic reaction initiator 52 may include a trigger mechanism 74 that senses for, or determines the occurrence of, one or more predetermined events (e.g., a predetermined temperature and/or pressure, or passage of a predetermined amount of time, or a signal, or any combination thereof). Once the exothermic reaction (e.g., an alloying reaction) is initiated between the two or more metallic constituents within the pre-event frac-ball material, the aforesaid exothermic reaction causes the pre-event frac-ball material to transition to a post-event frac-ball material. In some embodiments, the exothermic reaction may initiate at one or more given locations in or on the pre-event frac-ball 48 and may subsequently propagate within the frac-ball material until all of the pre-event frac-ball material has transitioned (e.g., undergone an alloying reaction) to a post-event frac-ball material. A frac-ball 48 comprising post-event frac-ball material is not capable of functioning as a segmentation device sealing element in a well environment; e.g., one or more mechanical properties of the post-event frac-ball material have changed in a manner wherein the frac-ball 48 is no longer capable of functioning as a segmentation device sealing element in a well environment. The present disclosure does not require the entirety of the pre-event frac-ball material to transition to a post-event frac-ball material; i.e., transitioning a portion of the pre-event frac-ball material to post-event frac-ball material may be sufficient to make the frac-ball 48 no longer capable of functioning as a segmentation device sealing element in a well environment. A propagating exothermic reaction is not, therefore, required. One or more local exothermic reactions may be adequate to transform the frac-ball 48 to a form that is no longer capable of functioning as a segmentation device sealing element in a well environment.

Using a frac-ball 48 having a pre-event body material that includes an aluminum metallic constituent and a magnesium metallic constituent as an example, powered forms of the aluminum metallic constituent and the magnesium metallic constituent may be formed into a frac-ball 48 using a formation process such as isostatic pressing. In the pre-event form, the frac-ball 48 formed by an isostatic pressing process possesses one or more mechanical properties adequate to permit the frac-ball 48 to function as a segmentation device sealing element in a well environment. Upon an exothermic reaction being initiated by the exothermic reaction initiator 52, the aforesaid aluminum and magnesium metallic constituents undergo an exothermic alloying reaction, thereby forming one or more Al—Mg alloys and transforming the frac-ball 48 to a “post-event form”. The one or more Al—Mg alloys do not possess mechanical properties adequate to enable the frac-ball 48 to function as a segmentation device sealing element in a well environment post event. As a result, the frac-ball 48 mechanically fails and no longer provides a sealing function within the segmentation device. As stated above, the present disclosure is not limited to a frac-ball 48 having a body material that includes an aluminum metallic constituent and a magnesium metallic constituent.

According to an aspect of the present disclosure, a method of operating a segmentation device disposed within a well casing is provided utilizing embodiments of the segmentation devices and frac-balls 48 described above. The method includes disposing a frac-ball 48 as described above in communication with the segmentation device to create a fluidic seal within the well casing. The present disclosure is not limited to any particular methodology for introducing a frac-ball 48 into the well casing, or for use with any particular type of segmentation device. Segmentation devices are typically configured to permit fluid flow through a passage; i.e., fluid flow between a forward end of the passage and an aft end of the passage. The term “forward end” refers to the end of the passage disposed closest to the well head when disposed within the casing, and the term “aft end” refers to the end of the passage disposed farthest from the well head when disposed within the casing. The passage typically has a ball seat that is configured to receive a frac-ball 48 (e.g., a spherical frac-ball 48 is received within a truncated conical-shaped ball seat. To segment the well casing, a frac-ball 48 is introduced into the casing and the frac-ball 48 is carried with fluid flow until it reaches the ball seat. Once the frac-ball 48 is seated properly within the seat, the frac-ball 48 closes the segmentation device fluid passage and substantially prevents fluid passage there through. The fluid on one side of the segmentation device may then be increased dramatically in pressure; e.g., to perform the perforation/fracturing process.

Subsequently, when the operator desires to re-open the segmentation device fluid passage, the exothermic reaction initiator 52 may be selectively actuated to initiate an exothermic reaction between the at least two dissimilar metallic constituents within the frac-ball body material. As stated above, the selective actuation of the exothermic reaction initiator 52 may be accomplished in a variety of different ways (e.g., by configuring a trigger mechanism 74 with a temperature sensor and logic that actuates the device upon a predetermined temperature threshold being reached, or configuring a trigger mechanism 74 with a pressure sensor and logic that actuates the device upon a predetermined pressure threshold being reached, or configuring a trigger mechanism 74 with a timer and logic that actuates the device after a predetermined period of time has expired, or configuring a trigger mechanism 74 with a signal sensor and logic that actuates the device upon a predetermined signal being received, or configuring a trigger mechanism 74 with a magnetic field sensor and logic that actuates the device upon a magnetic field being applied, removed, or altered, etc., or any combination thereof). Once the exothermic reaction (or multiple exothermic reactions) is complete, the frac-ball body material is transformed to a “post-event form” that does not possess mechanical properties adequate to enable the frac-ball 48 to function as a segmentation device sealing element in a well environment. As a result, the frac-ball 48 mechanically fails and no longer provides a sealing function within the segmentation device.

Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and the scope of the invention. 

What is claimed is:
 1. A frac-ball, comprising: a body comprising a material having at least two dissimilar metallic constituents, which dissimilar metallic constituents are configured to permit an exothermic reaction there between; and an exothermic reaction initiator in communication with the body, the exothermic reaction initiator configured to selectively initiate an exothermic reaction between the two dissimilar metallic constituents.
 2. The frac-ball of claim 1, wherein the at least two dissimilar metallic constituents are configured to participate in an alloying reaction there between upon being subjected to an input from the exothermic reaction initiator.
 3. The frac-ball of claim 2, wherein the at least two dissimilar metallic constituents are present within the material in relative amounts sufficient to sustain the exothermic reaction.
 4. The frac-ball of claim 2, wherein the at least two dissimilar metallic constituents include an aluminum metallic constituent and a magnesium metallic constituent.
 5. The frac-ball of claim 1, wherein the body has a shell configuration with an interior cavity.
 6. The frac-ball of claim 1, wherein the body has a solid body configuration.
 7. The frac-ball of claim 1 wherein the exothermic reaction initiator includes a trigger mechanism.
 8. A well casing segmentation system, comprising: a segmentation device; and a frac-ball having: a body comprising a material having at least two dissimilar metallic constituents, which dissimilar metallic constituents are configured to permit an exothermic reaction there between; and an exothermic reaction initiator in communication with the body, the exothermic reaction initiator configured to selectively initiate an exothermic reaction between the two dissimilar metallic constituents; wherein the frac-ball is configured to function as a seal within the segmentation device disposed in a well casing environment prior to an exothermic reaction, and subsequent to an exothermic reaction is incapable of functioning as a seal within the segmentation device disposed in the well casing environment.
 9. The system of claim 8, wherein the at least two dissimilar metallic constituents are configured to participate in an alloying reaction there between upon being subjected to an input from the exothermic reaction initiator.
 10. The system of claim 9, wherein the at least two dissimilar metallic constituents are present within the material in relative amounts sufficient to sustain the exothermic reaction.
 11. The system of claim 9, wherein the at least two dissimilar metallic constituents include an aluminum metallic constituent and a magnesium metallic constituent.
 12. The system of claim 8, wherein the body has a shell configuration with an interior cavity.
 13. The system of claim 8, wherein the body has a solid body configuration.
 14. The system of claim 8 wherein the exothermic reaction initiator includes a trigger mechanism.
 15. A method of operating a segmentation device disposed within a well casing, comprising: providing a segmentation device and a frac-ball, wherein the frac-ball includes a body comprising a material having at least two dissimilar metallic constituents, which dissimilar metallic constituents are configured to permit an exothermic reaction there between, and an exothermic reaction initiator in communication with the body, the exothermic reaction initiator configured to selectively initiate an exothermic reaction between the two dissimilar metallic constituents; disposing the frac-ball in communication with the segmentation device to create a fluidic seal within the segmentation device, wherein said fluidic seal substantially prevents fluid flow through the segmentation device; and selectively actuating the exothermic reaction initiator to initiate an exothermic reaction between the at least two dissimilar metallic constituents.
 16. The method of claim 15, wherein the at least two dissimilar metallic constituents are configured to participate in an alloying reaction there between upon the exothermic reaction initiator being selectively actuated.
 17. The method of claim 16, wherein the at least two dissimilar metallic constituents include an aluminum metallic constituent and a magnesium metallic constituent.
 18. The method of claim 17, wherein the exothermic reaction initiator includes a trigger mechanism that includes one or more of a pressure sensor, a temperature sensor, and a timing device.
 19. The method of claim 18, further comprising using the trigger mechanism to sense pressure within a well casing environment and actuating the trigger mechanism upon sensing a well casing environment pressure at or above a predetermined pressure.
 20. The method of claim 18, further comprising using the trigger mechanism to sense temperature within a well casing environment and actuating the trigger mechanism upon sensing a well casing environment temperature at or above a predetermined temperature.
 21. The method of claim 18, further comprising using the trigger mechanism to determine an amount of time passing subsequent to an occurrence of a predetermined event, and actuating the trigger mechanism upon a determination of a predetermined amount of time passing subsequent to the predetermined event. 